Laysan Duck vs Brent Goose
Anas laysanensis 对比 Branta bernicla
Side-by-Side Comparison
| 属性 | Laysan Duck | Brent Goose |
|---|---|---|
| 学名 | Anas laysanensis | Branta bernicla |
| 目 | Anseriformes | Anseriformes |
| 科 | Anatidae | Anatidae |
| 保护状况 | Critically Endangered | Least Concern |
| 体长 | — | — |
| 翼展 | 39.7 cm (15.6 in) | 63.9 cm (25.2 in) |
| 体重 | 465.25 g (16.41 oz) | 1335.0 g (47.09 oz) |
| 食性 | Dives for small fish, aquatic invertebrates, and amphibians; serrated bill grips prey; diet fish-heavy in … | Primarily herbivorous; grazes aquatic plants, grasses, and sedges; swans upend in shallow water for submerged … |
| 产卵数 | 9-13 | 1-10 |
| Population Trend | — | — |
Habitat Comparison
Laysan Duck
Restricted to Laysan Island and Midway Atoll in the Hawaiian Islands. Inhabits the central hypersaline lagoon and surrounding vegetation. Feeds on brine shrimp and flies around the lagoon margin.
Brent Goose
Breeds on high-Arctic tundra; winters on estuaries, coastal mudflats, saltmarshes, and sea-grass beds along Atlantic and Pacific coastlines. One of the most strictly coastal wintering geese.
Song & Call Comparison
Laysan Duck
Female gives a soft, muffled quacking series; male utters a quiet rasp. Extremely rare; the soft, unobtrusive quacking calls are seldom heard on the remote Laysan Island lagoon.
Brent Goose
A low, guttural 'rronk' or 'ronk-ronk' from flocks. Soft nasal calls in feeding groups. A subtle, understated call for a goose — less loud than most Anser geese.
Geographic Range & Migration
Laysan Duck
Resident in West Africa from Senegal to Nigeria; inhabits rainforest streams and swamps. Sedentary and locally common.
Brent Goose
Breeds across boreal and subarctic Canada and Alaska; winters in the southern United States, Mexico, and Central America.
保护状况
Laysan Duck
Brent Goose
How to Tell Them Apart
Laysan Duck
Brown plumage mottled and streaked buff and dark brown. White eye-ring contrasts with dark face. Both sexes similar; females show reduced white eye ring. Iridescent speculum. Critically endangered; only on …
Brent Goose
Small; mostly black head, neck, and breast. Small white neck-patch on adults. Back dark brownish-gray; belly pale gray to white depending on subspecies. White undertail coverts. Sexes similar.
About These Birds
Laysan Duck
莱岛鸭是世界上最濒危的鸭类之一，仅分布于夏威夷莱岛群岛的莱桑岛。这种小型鸭子由于长期与世隔绝，几乎完全失去了飞行能力。其种群曾一度减少至仅约12只，经过保护努力数量有所恢复。它主要以昆虫、无脊椎动物和藻类为食，面临外来物种入侵的严峻威胁。
Brent Goose
黑雁是小型海雁，繁殖于北极苔原，越冬于温带沿海地区。全身黑色，颈部有白色斑纹，腹部浅色或深色（因亚种而异）。以海草（大叶藻）和潮间带植物为食，高度依赖沿海湿地。在欧洲和北美分布有多个亚种，其中部分亚种数量因大叶藻减少而受到威胁。